TurboTommy

Hi all;
Usually while cranking (fuel and/or spark disconnected), I would see oil pressure on the stock gauge after about 15 seconds, cold engine.
All of a sudden, now, I don't see any oil pressure at all after endless cranking (practically draining the battery).
Some techs have told me that the real test is to just fire up the engine and see if the oil pressure comes up in a few seconds. I don't see the merits in doing that for fear that a small amount of damage could start to set in if I have no oil pressure for even 15 seconds of a running engine.

I'm thinking maybe the stock gauge is bad or maybe the oil filter is bad/totally drained. So I decided to take the filter off. Somebody else cranked the engine while I watched. There is oil being pumped out of the filter housing, but very little (maybe 50 milli-liters in 15 seconds of cranking) I know it's only cranking speed, but I figured it should be more than that.
Has any body here have an idea about this?

Also, what is the flow of oil? What I see is that the oil starts out pumped to the outside of the filter, through the filter, then through the center hole of the filter housing. I would guess then through the oil cooler and then to the engine; correct? Where does the gauge pick up the pressure signal; after it goes through the oil filter?

Tom M'Guinn

What's the background on this? Motor recently apart? Try pulling the plugs and DME relay to build more RPMs without starting it, and shoot a little compressed air in the dipstick tube. The most common causes would seem to be:


Priming issue --see above
Main pulley issues -- not torqued to 150lbs; washer backwards; not seated cleanly, etc.
OPRV -- hanging up, not sealing/working, etc.
Pick-up tube -- cracked and unable to suck up oil
Some rare/unusual mechanical wear/break/blockage somewhere

V2Rocket

oil goes pump>oil cooler>outside of filter>inside of filter>engine block

it doesn't measure oil pressure until after its gone thru the filter.

if you have the filter off try pouring some oil down the holes to "prime" the pump a little bit.

is your oil level low?

gruhsy

Can you attach an aftermarket oil pressure gauge?

I bought the Lindsey oil pressure gauge adapter for mine...super easy to install. Might give you a quick answer to rule out stock gauge.

TurboTommy

Okay so:
3 liter motor, built 10 years ago, never apart since then, always working great, always would build about 2.5 bar pressure on the stock gauge after cranking cold engine, in 15 seconds (I would do this the odd time when car would sit for longer periods of time)
Last time I started the car was about a month ago and did notice pressure taking a little longer than usual to come up. I just thought that maybe sometimes a filter that's not that good lets oil drain out after time. (It was like after an oil and filter change.)
Oil pressure was fine during that day of driving.
Fast forward to now, a month later, and the issue is as described above. Oil level is around the half way mark, maybe a little less.
I don't see the merits in trying to crank engine any faster when it always was making oil pressure before. (It always cranks pretty fast anyway; good battery and high overlap cam with less dynamic compression.)

I'm just trying to see if anybody has ever witnessed how much oil comes out of the filter housing during cranking revs; before I jump to conclusions and tow the car.

V2Rocket;
thanks for clarifying oil flow
However, can't see how one could prime the pump pouring oil down the holes, when the pump would need oil "from the inside" to get primed
(Or would the "air-exposed" oil filter housing cause an air lock or something?)

Yes Tom; those issues you listed is what I fear.

Tom M'Guinn

Sounds to me like you just lost your prime -- maybe a bad check valve in the head? At any rate, when I first started my 3 liter, I couldn't get it to prime until I pulled the plugs and relay and let it spin much faster, which worked like a charm.

Humboldtgrin

Like said, pull out the OPRV and pump oil in that OPRV hole back to the oil pump. Good time to check the OPRV o-rings. Check your crankshaft bolt to make sure it hasn't backed off, the torque on that crank bolt is the only thing holding the oil pump drive gear. And if that hasn't worked then take off your oil pan and replace your pickup tube seals and inspect the pickup tube. Good time to check your rod bearings.

cruise98

check the crank bolt. I would change the oil filter and prime the pump while it is off.

Chris White

crank it with the oil filter removed....it will prime and spew out oil quickly (make sure you have a spotter to yell 'stop')